diff --git a/desktop/scripts/check-file-sizes.mjs b/desktop/scripts/check-file-sizes.mjs
index 64c80991b..b49c9c1d3 100644
--- a/desktop/scripts/check-file-sizes.mjs
+++ b/desktop/scripts/check-file-sizes.mjs
@@ -87,7 +87,8 @@ const overrides = new Map([
   // 3-phase (stage/stop/commit) + commit_cascade_agents injectable helper for
   // retry-safety. Load-bearing reviewer-required change; queued to split.
   // Consolidation removed the legacy persona-card import/export codecs.
-  ["src-tauri/src/commands/personas/mod.rs", 984],
+  // internal-local-relay-lockdown round 5: preflight linked-agent profile updates.
+  ["src-tauri/src/commands/personas/mod.rs", 1018],
   // #1418 read-path fix: get_thread_replies' blocker fix (shared TIMELINE_KINDS
   // const + build_thread_replies_filter helper, mirroring the channel sibling so
   // the two p-gate filters can't drift) plus two guard unit tests. The file was
diff --git a/desktop/src-tauri/src/commands/agents.rs b/desktop/src-tauri/src/commands/agents.rs
index 2cbf6a4b3..40a0eddce 100644
--- a/desktop/src-tauri/src/commands/agents.rs
+++ b/desktop/src-tauri/src/commands/agents.rs
@@ -1083,6 +1083,7 @@ pub async fn start_managed_agent(
 
         let reconcile = ProfileReconcileData {
             private_key_nsec: record.private_key_nsec.clone(),
+            backend: record.backend.clone(),
             name: record.name.clone(),
             relay_url: record.relay_url.clone(),
             avatar_url: record.avatar_url.clone(),
@@ -1325,7 +1326,7 @@ pub(crate) use deploy::resolve_deploy_model_provider;
 #[path = "agents_profile.rs"]
 mod profile;
 #[cfg(test)]
-use profile::{profile_needs_sync, resolve_legacy_avatar};
+use profile::{profile_needs_sync, resolve_legacy_avatar, validate_profile_reconcile_relay_with};
 pub(crate) use profile::{reconcile_agent_profile, ProfileReconcileData};
 
 #[cfg(test)]
diff --git a/desktop/src-tauri/src/commands/agents_profile.rs b/desktop/src-tauri/src/commands/agents_profile.rs
index 0675d4c48..cab45ec3f 100644
--- a/desktop/src-tauri/src/commands/agents_profile.rs
+++ b/desktop/src-tauri/src/commands/agents_profile.rs
@@ -11,6 +11,7 @@ use super::*;
 
 pub(crate) struct ProfileReconcileData {
     pub(crate) private_key_nsec: String,
+    pub(crate) backend: BackendKind,
     pub(crate) name: String,
     pub(crate) relay_url: String,
     /// Expected avatar URL for the published profile. `None` for legacy records
@@ -49,6 +50,17 @@ pub(super) fn resolve_legacy_avatar(
         .unwrap_or_default()
 }
 
+pub(super) fn validate_profile_reconcile_relay_with<F>(
+    data: &ProfileReconcileData,
+    workspace_relay_url: &str,
+    validate: F,
+) -> Result<(), String>
+where
+    F: FnOnce(&BackendKind, &str, &str) -> Result<(), String>,
+{
+    validate(&data.backend, &data.relay_url, workspace_relay_url)
+}
+
 /// Reconcile an agent's kind:0 profile on the relay.
 ///
 /// Queries the relay for the agent's existing profile and re-publishes if missing
@@ -74,13 +86,6 @@ pub(crate) async fn reconcile_agent_profile(
 ) -> Result<(), String> {
     use crate::relay::{query_agent_profile, sync_managed_agent_profile};
 
-    // An explicit per-agent relay wins; an empty one falls back to the active
-    // workspace relay. Resolved once and used for both the read and write-back.
-    let relay_url = crate::relay::effective_agent_relay_url(
-        &data.relay_url,
-        &relay_ws_url_with_override(state),
-    );
-
     if !state
         .managed_agent_profile_reconcile_enabled
         .load(std::sync::atomic::Ordering::Acquire)
@@ -88,6 +93,19 @@ pub(crate) async fn reconcile_agent_profile(
         return Ok(());
     }
 
+    let workspace_relay_url = relay_ws_url_with_override(state);
+    validate_profile_reconcile_relay_with(
+        data,
+        &workspace_relay_url,
+        |backend, pin, workspace| {
+            crate::managed_agents::validate_effective_local_agent_relay(backend, pin, workspace)
+        },
+    )?;
+
+    // An explicit per-agent relay wins; an empty one falls back to the active
+    // workspace relay. Resolved once and used for both the read and write-back.
+    let relay_url = crate::relay::effective_agent_relay_url(&data.relay_url, &workspace_relay_url);
+
     // Query the relay for the agent's existing kind:0 profile.
     let existing = query_agent_profile(state, &relay_url, agent_pubkey).await?;
 
diff --git a/desktop/src-tauri/src/commands/agents_tests.rs b/desktop/src-tauri/src/commands/agents_tests.rs
index 1b2e0ed17..ca443615e 100644
--- a/desktop/src-tauri/src/commands/agents_tests.rs
+++ b/desktop/src-tauri/src/commands/agents_tests.rs
@@ -414,3 +414,32 @@ fn deploy_payload_carries_the_full_behavioral_quad() {
     assert_eq!(payload["provider"], "openai");
     assert_eq!(payload["relay_url"], "wss://relay.example");
 }
+
+#[test]
+fn profile_reconcile_preflights_legacy_empty_pin_before_relay_io() {
+    let data = ProfileReconcileData {
+        private_key_nsec: String::new(),
+        backend: BackendKind::Local,
+        name: "legacy".into(),
+        relay_url: String::new(),
+        avatar_url: None,
+        auth_tag: None,
+        pubkey: "pubkey".into(),
+        agent_command: "goose".into(),
+        persona_id: None,
+    };
+    let calls = std::cell::Cell::new(0);
+    let result = validate_profile_reconcile_relay_with(
+        &data,
+        "wss://public.example",
+        |backend, pin, workspace| {
+            calls.set(calls.get() + 1);
+            assert_eq!(backend, &BackendKind::Local);
+            assert!(pin.is_empty());
+            assert_eq!(workspace, "wss://public.example");
+            Err("blocked before query".into())
+        },
+    );
+    assert_eq!(result.unwrap_err(), "blocked before query");
+    assert_eq!(calls.get(), 1);
+}
diff --git a/desktop/src-tauri/src/commands/personas/mod.rs b/desktop/src-tauri/src/commands/personas/mod.rs
index 7752d5567..9e8c5f978 100644
--- a/desktop/src-tauri/src/commands/personas/mod.rs
+++ b/desktop/src-tauri/src/commands/personas/mod.rs
@@ -144,6 +144,24 @@ fn propagate_persona_name_rename(
     renamed
 }
 
+fn validate_persona_profile_updates_with<F>(
+    records: &[ManagedAgentRecord],
+    persona_id: &str,
+    old_display_name: &str,
+    name_changed: bool,
+    avatar_changed: bool,
+    mut validate: F,
+) -> Result<(), String>
+where
+    F: FnMut(&ManagedAgentRecord) -> Result<(), String>,
+{
+    records
+        .iter()
+        .filter(|record| record.persona_id.as_deref() == Some(persona_id))
+        .filter(|record| avatar_changed || (name_changed && record.name == old_display_name))
+        .try_for_each(&mut validate)
+}
+
 #[tauri::command]
 pub async fn update_persona(
     input: UpdatePersonaRequest,
@@ -176,10 +194,32 @@ pub async fn update_persona(
                 .find(|record| record.id == input.id)
                 .ok_or_else(|| format!("agent {} not found", input.id))?;
 
-            // Track what changed so we can propagate to linked agent records.
+            // Track what changed so we can preflight every linked agent before
+            // mutating either store or enqueueing agent-keyed profile I/O.
             let avatar_changed = persona.avatar_url != avatar_url;
             let name_changed = persona.display_name != display_name;
             let old_display_name = persona.display_name.clone();
+            let workspace_relay = crate::relay::relay_ws_url_with_override(&state);
+            let mut linked_records = if avatar_changed || name_changed {
+                let records = load_managed_agents(&app)?;
+                validate_persona_profile_updates_with(
+                    &records,
+                    &persona.id,
+                    &old_display_name,
+                    name_changed,
+                    avatar_changed,
+                    |record| {
+                        crate::managed_agents::validate_effective_local_agent_relay(
+                            &record.backend,
+                            &record.relay_url,
+                            &workspace_relay,
+                        )
+                    },
+                )?;
+                Some(records)
+            } else {
+                None
+            };
 
             persona.display_name = display_name;
             persona.avatar_url = avatar_url;
@@ -209,11 +249,9 @@ pub async fn update_persona(
 
             // If the avatar or display_name changed, propagate to linked agent
             // records and collect relay profile sync params for the async phase.
-            let sync_params: ProfileSyncParams = if avatar_changed || name_changed {
-                let mut records = load_managed_agents(&app)?;
+            let sync_params: ProfileSyncParams = if let Some(mut records) = linked_records.take() {
                 let mut params: ProfileSyncParams = Vec::new();
                 let mut agents_modified = false;
-                let workspace_relay = crate::relay::relay_ws_url_with_override(&state);
 
                 // Propagate the display_name rename to instances that still
                 // carry the old definition display_name (pool-named instances
diff --git a/desktop/src-tauri/src/commands/personas/name_propagation_tests.rs b/desktop/src-tauri/src/commands/personas/name_propagation_tests.rs
index ba855ccbd..732b8291f 100644
--- a/desktop/src-tauri/src/commands/personas/name_propagation_tests.rs
+++ b/desktop/src-tauri/src/commands/personas/name_propagation_tests.rs
@@ -156,3 +156,44 @@ fn test_rename_renames_all_matching_instances_in_one_pass() {
     assert_eq!(records[1].name, "Duncan Idaho");
     assert_eq!(records[2].name, "Birch", "pool-named instance untouched");
 }
+
+#[test]
+fn persona_profile_updates_preflight_only_records_that_would_mutate_or_publish() {
+    let mut records = vec![
+        agent("persona-1", "Paul", Some("Paul")),
+        agent("persona-1", "Birch", Some("Birch")),
+        agent("persona-2", "Paul", Some("Paul")),
+    ];
+    records[0].backend = crate::managed_agents::BackendKind::Local;
+    records[1].backend = crate::managed_agents::BackendKind::Provider {
+        id: "provider".into(),
+        config: serde_json::json!({}),
+    };
+    let visited = std::cell::RefCell::new(Vec::new());
+
+    validate_persona_profile_updates_with(&records, "persona-1", "Paul", true, false, |record| {
+        visited.borrow_mut().push(record.pubkey.clone());
+        Ok(())
+    })
+    .unwrap();
+    assert_eq!(*visited.borrow(), vec!["pubkey-Paul"]);
+
+    visited.borrow_mut().clear();
+    validate_persona_profile_updates_with(&records, "persona-1", "Paul", false, true, |record| {
+        visited.borrow_mut().push(record.pubkey.clone());
+        Ok(())
+    })
+    .unwrap();
+    assert_eq!(*visited.borrow(), vec!["pubkey-Paul", "pubkey-Birch"]);
+}
+
+#[test]
+fn persona_profile_preflight_failure_happens_before_name_mutation() {
+    let records = vec![agent("persona-1", "Paul", Some("Paul"))];
+    let result =
+        validate_persona_profile_updates_with(&records, "persona-1", "Paul", true, false, |_| {
+            Err("blocked".into())
+        });
+    assert_eq!(result.unwrap_err(), "blocked");
+    assert_eq!(records[0].name, "Paul");
+}
diff --git a/desktop/src-tauri/src/commands/personas/snapshot/import.rs b/desktop/src-tauri/src/commands/personas/snapshot/import.rs
index a9674cf6d..d0e0f658c 100644
--- a/desktop/src-tauri/src/commands/personas/snapshot/import.rs
+++ b/desktop/src-tauri/src/commands/personas/snapshot/import.rs
@@ -288,6 +288,20 @@ pub async fn preview_agent_snapshot_import(
     .map_err(|e| format!("spawn_blocking failed: {e}"))?
 }
 
+pub(super) fn validate_snapshot_import_relay_with<F>(
+    workspace_relay_url: &str,
+    validate: F,
+) -> Result<(), String>
+where
+    F: FnOnce(&crate::managed_agents::BackendKind, &str, &str) -> Result<(), String>,
+{
+    validate(
+        &crate::managed_agents::BackendKind::Local,
+        "",
+        workspace_relay_url,
+    )
+}
+
 // ── `confirm_agent_snapshot_import` ──────────────────────────────────────────
 
 /// Import a `buzz-agent-snapshot v1` file as a brand-new agent.
@@ -321,6 +335,13 @@ pub async fn confirm_agent_snapshot_import(
         return Err("Snapshot display name is empty.".to_string());
     }
 
+    // Snapshot imports always mint a local agent with an empty relay pin. Reject
+    // a disallowed effective workspace relay before key generation or store I/O.
+    let workspace_relay_url = relay_ws_url_with_override(&state);
+    validate_snapshot_import_relay_with(&workspace_relay_url, |backend, pin, workspace| {
+        crate::managed_agents::validate_effective_local_agent_relay(backend, pin, workspace)
+    })?;
+
     // ── Resolve behavioral defaults ──────────────────────────────────────────
     let minted = resolve_snapshot_import_behavior(
         snapshot.definition.respond_to.as_deref(),
diff --git a/desktop/src-tauri/src/commands/personas/snapshot/tests.rs b/desktop/src-tauri/src/commands/personas/snapshot/tests.rs
index b1d19f06b..f3d7bd828 100644
--- a/desktop/src-tauri/src/commands/personas/snapshot/tests.rs
+++ b/desktop/src-tauri/src/commands/personas/snapshot/tests.rs
@@ -1,6 +1,7 @@
 use super::import::{
     decode_snapshot_from_bytes, reject_legacy_persona_filename, resolve_snapshot_import_behavior,
-    AgentSnapshotImportResult, MAX_SNAPSHOT_JSON_BYTES, MAX_SNAPSHOT_PNG_BYTES,
+    validate_snapshot_import_relay_with, AgentSnapshotImportResult, MAX_SNAPSHOT_JSON_BYTES,
+    MAX_SNAPSHOT_PNG_BYTES,
 };
 use super::*;
 use crate::managed_agents::{
@@ -969,3 +970,18 @@ fn validate_encode_size_png_over_boundary_is_rejected() {
         "error must mention size limit, got: {err}"
     );
 }
+
+#[test]
+fn individual_snapshot_import_preflights_empty_pin_before_mint_or_store() {
+    let calls = std::cell::Cell::new(0);
+    let result =
+        validate_snapshot_import_relay_with("wss://public.example", |backend, pin, relay| {
+            calls.set(calls.get() + 1);
+            assert_eq!(backend, &BackendKind::Local);
+            assert!(pin.is_empty());
+            assert_eq!(relay, "wss://public.example");
+            Err("blocked before mutation".into())
+        });
+    assert_eq!(result.unwrap_err(), "blocked before mutation");
+    assert_eq!(calls.get(), 1);
+}
diff --git a/desktop/src-tauri/src/commands/team_snapshot.rs b/desktop/src-tauri/src/commands/team_snapshot.rs
index 268b31583..2b3ab4fc6 100644
--- a/desktop/src-tauri/src/commands/team_snapshot.rs
+++ b/desktop/src-tauri/src/commands/team_snapshot.rs
@@ -496,6 +496,20 @@ pub async fn preview_team_snapshot_import(
 ///
 /// Importing the same file twice yields two distinct teams with different
 /// agent keypairs (same as individual agent import).
+fn validate_team_snapshot_import_relay_with<F>(
+    workspace_relay_url: &str,
+    validate: F,
+) -> Result<(), String>
+where
+    F: FnOnce(&crate::managed_agents::BackendKind, &str, &str) -> Result<(), String>,
+{
+    validate(
+        &crate::managed_agents::BackendKind::Local,
+        "",
+        workspace_relay_url,
+    )
+}
+
 #[tauri::command]
 pub async fn confirm_team_snapshot_import(
     input: TeamSnapshotImportConfirm,
@@ -506,6 +520,13 @@ pub async fn confirm_team_snapshot_import(
     let snapshot = decode_team_snapshot_from_bytes(&input.file_bytes)?;
     let now = now_iso();
 
+    // Team snapshots mint only empty-pin local agents. Preflight the workspace
+    // relay once before generating any member key or mutating any store.
+    let workspace_relay_url = relay_ws_url_with_override(&state);
+    validate_team_snapshot_import_relay_with(&workspace_relay_url, |backend, pin, workspace| {
+        crate::managed_agents::validate_effective_local_agent_relay(backend, pin, workspace)
+    })?;
+
     // Resolve behavioral defaults for every member before any key generation.
     let definitions = build_import_definitions(&snapshot, input.keep_allowlist, &now)?;
     let persona_ids: Vec<String> = definitions.iter().map(|d| d.id.clone()).collect();
diff --git a/desktop/src-tauri/src/commands/team_snapshot/tests.rs b/desktop/src-tauri/src/commands/team_snapshot/tests.rs
index ca7dc6183..dd085f048 100644
--- a/desktop/src-tauri/src/commands/team_snapshot/tests.rs
+++ b/desktop/src-tauri/src/commands/team_snapshot/tests.rs
@@ -724,3 +724,18 @@ fn full_rollback_at_teams_boundary_absent_agents_store() {
     assert!(!teams_path.exists());
     assert_eq!(errors.len(), 1, "only the teams-write error");
 }
+
+#[test]
+fn team_snapshot_import_preflights_empty_pin_once_before_mint_or_store() {
+    let calls = std::cell::Cell::new(0);
+    let result =
+        validate_team_snapshot_import_relay_with("wss://public.example", |backend, pin, relay| {
+            calls.set(calls.get() + 1);
+            assert_eq!(backend, &crate::managed_agents::BackendKind::Local);
+            assert!(pin.is_empty());
+            assert_eq!(relay, "wss://public.example");
+            Err("blocked before mutation".into())
+        });
+    assert_eq!(result.unwrap_err(), "blocked before mutation");
+    assert_eq!(calls.get(), 1);
+}
diff --git a/desktop/src-tauri/src/managed_agents/restore.rs b/desktop/src-tauri/src/managed_agents/restore.rs
index fab481e12..8b2d601d0 100644
--- a/desktop/src-tauri/src/managed_agents/restore.rs
+++ b/desktop/src-tauri/src/managed_agents/restore.rs
@@ -422,6 +422,7 @@ pub async fn restore_managed_agents_on_launch(
                     pubkey.clone(),
                     crate::commands::ProfileReconcileData {
                         private_key_nsec: record.private_key_nsec.clone(),
+                        backend: record.backend.clone(),
                         name: record.name.clone(),
                         relay_url: record.relay_url.clone(),
                         avatar_url: record.avatar_url.clone(),